To illustrate another conversational capability, Figure REF  shows a screenshot of Bing in response to the query “convert string to int”. Note that here the search engine has responded with a clarification question [1]}, [2]} “What programming language are you looking for?” with a number of options. Beyond simply being a clarification question in a more conversational style, the use of “programming language” is again an example of a similar technique used in chatbots like XiaoIce. By introducing external knowledge (the query never mentioned “programming language”), the search engine introduces new information into the conversation rather than using a generic prompt such as “which of these would you like?” Similar to the studies on chatbots, [2]} provide evidence that the more specific question leads to higher engagement than the more general question. The reader are referred to Section REF  for an in-depth discussion of techniques.
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